• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.6
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• pp.687-692
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• 2010

The mass cultivation of Ecklonia cava Kjellman was studied as a potential biomass source for the extract industry in Korea. Experiments were conducted to investigate the optimal conditions for artificial seed production and mass cultivation of this species. Maximum growth and young thalli development in the nursery culture area occurred at 2 m depth, whereas maximum growth of thalli in the main culture area occurred at 1 m depth. Production of E. cava was between 2.6 and 3.6 kg wet wt. $m^{-1}$ after depth control and removal of fouling organism, etc. The relationship between optimal water depth for culture and underwater irradiance during the E. cava cultivation was calculated as: y = -0.718x + 8.042 ($r^2$=0.976). The growth rates achieved in this trial indicate that E. cava cultures could produce and supply sufficient biomass.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.6
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• pp.801-806
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• 2004

The pilot study was conducted to (i) investigate the ability of various membrane integrity monitoring methods to detect changes in membrane integrity during operation, and (ii) determine the impact of membrane damage on microbial removal by microfiltration. Two variations of air pressure hold tests were investigated for direct integrity monitoring: pressure decay (PD) and diffusive air flow (DAF) tests which are most commonly used integrity tests for microfiltration (MF) membranes. Both PD and DAF tests were sensitive enough to detect one damaged fiber out of 66,000 under field operaing conditions. Indirect integrity monitoring such as turbidity and particle counting, however, responded poorly to defects in membrane systems. Microbial challenge study was performed using both new and deliberately damaged membranes, as well as varying the state of fouling of the membrane. This study demonstrated that MF membrane with nominal pore size $0.2{\mu}m$ was capable of removing various pathogens including coliform, spore, and cryptosporidium, at the level required by drinking water regulations, even when high operating pressures were applied. A sharp decrease in average log reduction value (LRV) was observed when one fiber was damaged, emphasizing the importance of membrane integrity in control of microbial contamination.

• Journal of Power System Engineering
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• v.20 no.5
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• pp.37-45
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• 2016

Exhaust gas recirculation has the advantage of being low-cost and easy to control of NOx emission. Therefore, it is most generally used to reduce NOx emission according to strengthen regulation. In the case of a non-road engine, such as the agricultural engine, since it mainly operate a middle or high-load state, NOx emission is decreased in accordance with the mapping range of the EGR rate, but results in an increase in the particulate matter which is caused to deposit and fouling problem of the EGR system. This problem has become an important issue for maintaining the performance of the engine, as well as emission performance. This study had examined the effects of cooler aging on the performance of heat transfer efficiency and NOx emission in non-road diesel engine. As a result of the EGR cooler aging during 200 hours engine operation, the cooling performance decreased about 25% compared with that of fresh cooler and the NOx emission increased about 14.6% on NRSC(non-road steady cycle) and 20% on NRTC(non-road transient cycle) compared with that of fresh cooler respectively.

• Membrane Journal
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• v.9 no.4
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• pp.193-201
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• 1999

The object of study were the development of membrane process and the optimization of operation condition for membrane system, which was used the pre-treatment system of tap water treatment in steady of conventional process such as coagulation, sedimentation. The higher steady flux is very important factor, by a suitable pre-treatment and optimization of operating condition such as fouling control, crossflow and backwashing method, in membrane system. So, we were observed the effect of flux decline for membrane used by 4 type ultrafiltration(UF) membrane pre-treatment process, and optimized the operation condition of filtration system under various MWCO(Molecular weight cut-off), operation pressure, linear velocity and temperature to maintain higher flux. From these experiment, we were identified that UF process showed a slower flux decline rate and a higher flux recovery than microfiltration(MF) membrane. The water quality of UF permeate was better than that of MF, and was not effected pre-treatment process. In the operation condition, the rate of flux decline was diminished by a higher linear velocity and operation temperature, lower pressure.

• Journal of Navigation and Port Research
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• v.28 no.8
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• pp.767-773
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• 2004

IMO(International Maritime Organization) is strongly proceeding with adoption of a new maritime environmental convention and coming into r1fed for regulation enhancement about the pollutants which are happened in a ship recently. Study about the conventions that our country currently comes into r1fect, and there is during forwarding and correspondence must be performed effectively. In this paper, International convention on the control of harmful Anti-Fouling system on ship, Ballast water management, Prevention of air pollution from ships, treat a main pending problem in ocean related environmental regulation convention.

• Journal of Korean Society of Water and Wastewater
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• v.27 no.5
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• pp.529-545
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• 2013

With the increasing concern on climate changes and energy shortage, anaerobic membrane bioreactors (AnMBR) become a promising alternative to aerobic processes for domestic wastewater treatment. Two major advantages of AnMBRs are energy production and sludge reduction. Recently, several different configurations of AnMBRs have been proved to produce high quality effluent at reasonable hydraulic retention time and ambient temperature. One of the major problems of the AnMBR is membrane fouling control, and some solutions are already suggested. Other problems to be solved before the full application of the AnMBR are recovery of dissolved methane, management of residual nutrients and sulfide. Considering the potential advantages and future technology development, AnMBR will become major domestic wastewater treatment process in near future.

• International Journal of Naval Architecture and Ocean Engineering
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• v.13 no.1
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• pp.659-673
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• 2021

This study aims to investigate the impact of the High Pressure Selective Catalytic Reduction system (SCR-HP) on a large marine two-stroke engine performance parameters by employing thermodynamic modelling. A coupled model of the zero-dimensional type is extended to incorporate the modelling of the SCR-HP components and the Control Bypass Valve (CBV) block. This model is employed to simulate several scenarios representing the engine operation at both healthy and degraded conditions considering the compressor fouling and the SCR reactor clogging. The derived results are analysed to quantify the impact of the SCR-HP on the investigated engine performance. The SCR system pressure drop and the cylinder bypass valve flow cause an increase of the engine Specific Fuel Oil Consumption (SFOC) in the range 0.3-2.77 g/kWh. The thermal inertia of the SCR-HP is mainly attributed to the SCR reactor, which causes a delayed turbocharger response. These effects are more pronounced at low engine loads. This study supports the better understanding of the operating characteristics of marine two-stroke diesel engines equipped with the SCR-HP and quantification of the impact of the components degradation on the engine performance.

• Membrane Journal
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• v.23 no.3
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• pp.211-219
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• 2013

Effect of water back-flushing period (FT) was investigated in hybrid water treatment process of carbon ultrafiltration and polypropylene (PP) beads coated with photocatalyst, and membrane effect was studied by comparing the previous studies with carbon microfiltration or alumina ultrafiltration, microfiltration membranes. FT 6 min was the most effective to control initial membrane fouling and optimal condition because the membrane fouling resistance was low until initial 60 min and the maximum total permeate volume was acquired at this FT. The turbidity treatment efficiency was high beyond 98.6%, and did not depend on FT, which was same with the previous result of carbon or alumina microfiltration. The organic matters treatment efficiency was the highest value of 98.2% at FT 6 min, which was almost same trend with the previous result of alumina microfiltration. Then the organic matters treatment efficiency of carbon microfiltration was the minimum at no back-flushing (NBF) and increased as decreasing FT, but that of alumina ultrafiltration was the maximum at NBF and also increased as decreasing FT. Therefore it means that water back-flushing effect on the organic matters treatment efficiency had a different mechanism depending on pore size in spite of the same material membranes.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.1
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• pp.81-87
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• 2006

The industrial systems contain many sites and components susceptible to biofilms formation. Biofilms play an important role in microbial growth and industrial fouling. Thus, the control of the biofilms in industrial systems has been emphasized, however, the efficient controlling method was not provided yet. Since silver compounds have no residual and corrosion problem, the interest for silver compounds as a biofilm control disinfectant has been increased. In this study, we attempted to examine the disinfection ability of silver compounds. The disinfection efficiency of two silver compounds(silver ion and silver oxide) were evaluated for biofilms in comparison with suspended cells using well known indicator microorganisms(E. coli, P. aeruginosa) and compared with that of chlorine. Silver compounds were found to be effective in inactivating E. coli and P. aeruginosa biofilms. The reason for superiority of silver compounds as biofilm disinfectant was suggested by that silver can penetrate into the inner biofilm matrix faster than chlorine without consumption. This study reports that the disinfectant which is highly effective in inactivating the suspended cells in water becomes the less effective for controlling biofilm because of its high reactivity. This results imply that the effective strategy for biofilm control can be achieved by considering thoroughly the chemical nature of disinfects and biofilm structure and the reactivity between them.

• Journal of Korean Society of Water and Wastewater
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• v.19 no.1
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• pp.47-52
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• 2005

This study was conducted to evaluate the performance of submerged hollow fiber MF processes to treat secondary wastewater for water reuse. Specifically, membrane productivity and filtrate water quality were investigated under various operating conditions (i.e. flux, recovery, and backwash rate) at pilot-scale. Membrane fouling became more severe with increasing flux and recovery, suggesting that low flux operation (< 25 LMH) was desirable. At high flux operating(> 37.5 LMH), increasing backwash rate showed only limited success. The biofouling, quantified by PEPA and BFHPC, was also significant in wastewater reclamation, and biogrowth control by chlorine, were necessary to improve membrane productivity. Filtrate water qualities are in good compliance with water reuse regulations regardless of operating conditions (flux, recovery and backwash rate). Particle (e.g. turbidity) removal ranged from 89 to 98%, while only 11 to 21% of organics (e.g. NPDOC) were removed by MF membrane. Only small improvement in biostability (e.g. AOC) was achieved by MF system, and thus, without post disinfection, significant microorganisms might be present in the filtrate due to regrowth. Lastly, in order to further investigate pathogen removal, controlled microbial challenge tests were performed by monitoring Giardia, Cryptosporidium, bacteria and virus, and showed relatively good microbial removal.